This invention relates to an apparatus for inspecting defects on surfaces of columnar or cylindrical articles such as medicinal capsules or a machine for sorting empty capsules.
Each medical capsule is composed of a cap and a capsule body, and is formed by combining them. It is necessary that inspection of empty capsules is carried out to detect defects on the surfaces thereof prior to filling them with a drug. With regard to the defects of the capsules, there are well known faults such as holes, cracks, cutoffs and deformations due to which the capsules can be judged to be defective in appearance, and faults such as pinholes of 0.1 mm to 2 mm or so in diameter and thin spots each having a locally thinner wall thickness on the capsule, due to which faults the capsules are scarcely judged to be defective in appearance.
FIGS. 1A and 1B show a medicinal capsule. The capsule comprises a cap 1 and a body 2, and the cap 1 is provided with a lock hole (notch) 3 for locking it to the body 2. The capsule before packing a drug therein is called an empty capsule, and at this time the combined force between the cap 1 and the body 2 is small. Thus, the empty capsule is, so to speak, in a provisional combined state, as shown in FIG. 1A. After packing the drug, the capsule is in a real combined state, as shown in FIG. 1B in which the combined force between the cap 1 and the body 2 is large due to their being pressed against each other. In the capsules formed like this, a variety of defects will occur thereon sometimes at their manufacture. As the defects, for example, there are a thin spot where a wall thickness of the capsule is partially thin, a hole formed by the build-up of the thin spot, a pinhole, and a chipped cap in which a recess is present on a periphery of the opening of the cap. Further, in the manufactured capsules, defective capsules may be included, and as these defective capsules, there are a loose capsule in which the cap and the body are separated, a twin cap in which the separated cap is recombined with the normal capsule (i.e. non-defective capsule), and a locked capsule in the real combined state into which the empty capsule has been converted in transit. With regard to the medicinal capsules, they are generally classified into opaque capsules and transparent capsules in compliance with the presence and absence of titanium oxide therein, and in some cases, one of the body and the cap of each capsule is transparent and the other thereof is opaque. Therefore, in connection with the inspection of the capsules, a variety of defects mentioned above must be inspected in accordance with such a type of capsules, which fact makes its automation difficult. Hence, it is inevitable at present to rely upon a visual inspection. However, the visual inspection is limited in accuracy. Therefore to replace such a primitive inspection, an inspecting apparatus is now used which is described in Japanese Patent Publication No. 9897/1979 (which corresponds to U.S. Pat. No. 3,709,598) and in which an optical means is employed. The technique disclosed in this patent is as follows:
That is to say, FIG. 2 attached hereto exhibits the principle of the apparatus shown in the aforesaid patent, and in the drawing, reference numeral 4 represents an inspecting head, which has rollers 5 for spinning or rotating capsules disposed on the outer periphery thereof at predetermined intervals and can be rotated intermittently in a clockwise direction, as indicated by an arrow therein, around on a shaft 11. The respective rollers 5 for spinning or rotating the capsules can be rotated at a high speed in an arrow direction by means of a driving mechanism which is not shown. The inspecting head 4 has an air suction mechanism therein which can give suction effect to spaces between the rollers 5 via a suction chamber. The capsules 6 are successively fed in line from a separately disposed capsule feeding mechanism through a position of arrow p to the spaces between the rollers 5. At this time, the capsules 6 are sucked to the spaces therebetween by the air suction mechanism and are held there. Further, when the rollers 5 are rotated, the capsules 6 are correspondingly rotated at about the same speed as that of the rollers.
The capsules which are being held and rotated about the inspecting head 4 are subjected to defect inspection in transit thereof. An inspecting section where the defect inspection is carried out is composed of an illuminant lamp 7, an optical lenses 8, 9 and a light sensor 10. The light radiated from the illuminant lamp 7 reaches the surfaces of the capsules through the optical lens 8 in the form of a lengthwise strip belt and is hit along an axis of each capsule 6. The reflected light from the capsule 6 is reached to the light sensor 10 through the optical lens 9. FIG. 3 illustrates schematically the aspect in which the reflected light from the capsule 6 reaches the light sensor 10. The light sensor 10 is provided, on the light-receiving surface thereof, with a plurality of photocells 10' in parallel. The light which reaches the respective photocells 10' contains information about different parts on each capsule 6. Accordingly, defects on the surface of the capsule 6 can be inspected by measuring an output from each photocell 10'.
This inspecting apparatus permits automatic inspection of defects on the surface of the capsules and is more excellent than the visual inspection by inspectors. However, in the case that the inspection of very small faults such as pinholes is carried out, the above inspecting apparatus requires several tens of the photocells 10'. For example, when a pinhole of 0.5 mm in diameter on the capsule of 20 mm in length is detected, the photocells as many as 40 are required. Although each photocell is not so expensive, many photocells having similar characteristics must be arranged and much attention must be paid to their maintenance, because unless the characteristics of the respective photocells are the same, accurate inspection cannot be accomplished. Moreover, the increase in the number of the photocells correspondingly leads to an increase in judging circuits, and the apparatus becomes expensive.
An object of this invention is thus to provide an apparatus for inspecting faults on capsules, which apparatus can overcome the aforementioned drawbacks of the conventional technique, can inspect accurately very small defects on the surfaces of the capsules irrespective of a type of capsules, and is simple as well as compact in constitution.